The other thing we are doing a lot is to parse from/to selections in the page into MDX using simple {[timeDim].[fromPeriod]:[timeDim].[toPeriod]}

The main thing to watch out for is that both LastPeriods and : MDX operator are extremely sensitive to dimension leveling and indexing. So really don’t play well with TM1 time dimensions having lots of alternate rollups. In the “new world” of PA with proper alternate hierarchies this will cease to be a problem but it isn’t the world we are currently in so may require building one or more helper dimensions with sinle rollup or flat to generate the list of elements and then parsing that back in.